Various attempts have been made to attain high image quality of a video displayed on an image display device. Besides resolution, luminance and chromaticity are used as criteria for expressing a quality of the video. In recent years, standards such as so-called HDR (High Dynamic Range) and XDR (X-tended Dynamic Range) have been suggested as standards for defining a luminance gradation having a range wider than ever; for example, the former includes SMPTE ST2084 as a standard and the latter includes a standard such as ARIB STD-B67 (see Non Patent Literatures 1 and 2 described below). Furthermore, for example, ITU-R BT.2020 has been proposed as a standard with a color gamut expanded more than ever (see Non Patent Literature 3 described below).
These standards widely define video signals as faithfully as possible to a recorded original video so as to minimize compression of information such as luminance or chromaticity of the video whereas image display devices are often unable to fully cover video signals extending over such a wide domain of definition due to technical difficulties. Even when trying to display a video based on video signals according to the aforementioned standards on an image display device, luminance and chromaticity are reproduced only within a range of display performance of the image display device in the video actually displayed. In addition, image display devices have individual differences. Thus, in order to grasp a level of performance actually provided by a certain image display device with respect to each of the standards mentioned above, there is a necessity of displaying a video on the image display device to individually measure luminance or chroma thereof.
Such a measurement may be manually performed by using a luminance or chromaticity meter. When displayable luminance is to be measured on a certain image display device, for example, a test pattern is displayed on a screen of the target image display device and luminance of the screen is measured; thus, luminance may be grasped as a numerical value. As regards a color range, for example, several kinds of color test patterns on single colors are displayed and the chromaticity of the screen is measured with a chromaticity meter; thus, characteristics on display of colors may be grasped.